Not to sound negative about someone's idea, but maybe it would help to try and visualize the flow of energy in a vaping "system".
The charge in the battery (not an infinite surce like a PT) flows into the heater and is converted into thermal energy.
From an initial state of "room temperature" the atty heater gets hot, vaporizes juice, then cools. Some of the heat generated is conducted and radiated to the atty shell, which is them conduced or radiated away. If we consider a single puff situation, the temperatures would return to room temperature before the next puff. Not many of us vape that way
With repetitive puffs, the heat input into the atty shell is faster than the heat loss, so the shell heats up. The faster we puff, the more heat energy is stored in the shell. With each new puff the atty heats up, vaporizes juice, loses some heat to the shell, the shell heats up more, then we start the "between puff" heat loss. Try and visualize this heat flow as you puff. You send a blob of electricity into the heater, and you got part of a blob of heat that produces vapor and part of a blob that heats the shell.
If the shell is kept cool through conduction, radiation, or convection like is necessary with a CPU chip, then each blob of electricity that goes to the cooler heater will have to heat it up to produce a blob of heat to make vapor, and a little bit bigger blob to heat up the cooler shell. Each puff will require a bigger blob of electricity to produce vapor. Even more heat will be lost to heat up the shell that is constantly being cooled. In fact, you will be sending heat out into the room, on purpose. Each puff that heats up the heater, sends heat to the shell, is radiated (efficiently) into the room, consumes more battery energy than an insulated atty shell would. All of this heat energy is produced by the overworked little heater inside the atty. Poor thing.
Heater resistance is a little lower when cool. Starting with a cool atty, low resistance=more current though the wire, and heating it up, produces mechanical stresses proportional to the change in temperature. This is similar to the resistance Vs temperature Vs life of an incandescent light bulb, except we don't get the heater hot enough to vaporize the heater material itself. If you got the heater and shell hot enough to vape by it self, stop puffing
I agree that overheating the atty heater wire shortens it's life and a shell that is completely insulated might raise heater temperature by reducing heat loss, but radiating more heat from the system will require the heater to work harder, less efficiently, and pump heat out into the space around it. Most things die early when they have to work harder.
The idea of a heat sink is a great way to keep electrical parts from going over a destructive upper temperature, but we are trying to heat up the atty heater wire. Until the atty heater gets up to that temperature, we don't vape.
Again, just my input, not trying to be negative about your idea, and my position may change as I think about this more
